Fire retardant compositions containing nitrogen-phosphorous-halogen adducts

ABSTRACT

A process of producing flame resistant layers, which comprises treating cured resins or cured formed resinous bodies with the vapor of phosphorus trichloride and thereafter subjecting the treated resins to the vapors of ammonia. Satisfactory flame resistance is given by concentrations of the halide moiety of between 5 and 20 percent by weight of the resin.

United States Patent [191 Braude et al.

[ Aug. 21, 1973 FIRE RETARDANT COMPOSITIONS CONTAININGNITROGEN-PHOSPI-IOROUS-I'IALOGEN ADDUCTS [75] Inventors: George L.Brande; Eldon E. Stahly,

both of Ellicott City, Md.

[73] Assignee: W. R. Grace & Co., Washington Research Center, Columbia,Md.

[22] Filed: Nov. 30, 1971 [21] Appl. No.: 203,420

[52] US. Cl. 117/138, 117/621, 117/138.8 F,

ll7/138.8 D [51] Int. Cl 844d l/22 [58] Field of Search 117/136, 138,138.8 F,

l17/138.8 D, 138.8 A, 161 KP, 161 ZB, 106 R, 62, 62.1, 47 A; 252/8.l;106/15 FP; 260/25 PF [56] References Cited UNITED STATES PATENTS3,132,045 5/1964 Hill. 117/138 Primary Examiner-William D. MartinAssistant Examiner-Theodore G. Davis Attorney-Richard P. Plunkett et a1.

[ 5 7] ABSTRACT 4 Claims, No Drawings FIRE RETARDANT COMPOSITIONSCONTAINING NITROGEN-PHOSPHOROUS-IIALOGEN ADDUCTS This invention relatesto compositions which, when added to polyester or epoxy resins and inspecial circumstances grafted onto the surface molecules of alpha-olefinshapes, give substantial fire retardancy to the entire resinous mass.

Prior art of fire retardant compositions effective in like circumstanceswill disclose that the reaction products of phosphorus halides andoxyhalides with ammonia and amines have been used. However, thecompositions lost the halide as soon as they were combined with theresin, and thus a large portion of the potential fire retardancy ofthese compositions is lost at the time of the resin cure. The presentcompositions are distinguished from those of the prior art known to usby retaining substantially all of the halide in the mixed resincomposition, and therefore the fire retardance of these compositions ismaterially increased.

Although about weight percent of the complex will produce effective fireresistance, the effectiveness of some of these compounds is such that aslittle as 5 weight percent added to the resin will impart nonburningcharacteristics, conforming to ASTM standards. The compositions possessthe advantage of et fectiveness over long periods of time. Although,according to the prior art, considerable fire retardancy was achieved bythe use of the adducts of phosphorus halides, the volatility of theuseful halogen compounds was sufficient to cause the progressive loss offlameresistant characteristics.

In contrast, in the present invention the halide moieties remain in theresin compositions. Long time combustion retardancy results.

The combination of these metal, metaloid of phosphorus halides (MX) withammonia or amines produces the complex or coordination compounds whichare added to the resin or milled intothe mass preliminarily to anymolding or sheeting-out operations.

In our invention, we utilize the simple adducts of phosphorus chloride(PCl and P0,), and of nitrogen compounds such as ammonia, urea, ammoniumsulfocyanide, hexamethylene tetramine, isocyanuric acid, cyanuric acidand the like. In place of phosphorus, effective adducts can also beproduced using the follow ing elements and radicals: B, Al, Sn, Ti, Si,PO, PS, Sb, SbO, V, V0, As and S. So,by our process we combine all threeelements, phosphorus or its equivalents, nitrogen and halogen incompatible low-cost additives which may be incorporated in plasticbodies or in coatings for plastic and other combustible materials.

When incorporated in polyester and epoxy resins, phenolic resins,polyurethanes, novolak-epoxy resins and polystyrene, or associated withthe alpha-olefins as will later appear, the halogen is not released asthe resin is cured. In contrast to compounds of the prior art, thehalogen contributes permanently to the fire retardancy of thecomposition. In a further surprising aspect of the invention, we havefound that effective flameproofing treatment can be given to the mass ofresin after it has been shaped or formed. It is not necessary toincorporate the fire retardant complexes in the resin prior to anymolding or sheeting operation Surprisingly, we have found thatphosphorus, metal or metaloid halides (MX) possess the ability todiffuse into the resinous mass which thereafter can be reacted with theammonia or amine to produce, in the. surface layers of the mass atleast, substantial degrees of fire retardancy. Diffusion of the MXcompound into the resin can take place when these compounds either areliquids or are vapors, and results in effective flame resistant resinproducts. The MX compound must be used in the vapor phase when the resinis soluble in the liquid. As an example of this: polystyrene dissolvesin liquid PCl,. Therefore, gaseous PCl, must be used to produce thedesired result.

The uncured resins which are made fire resistant by this processcomprise polyesters containing about 10-45 percent and preferably 2040percent by weight of molecular styrene or a similar ethylenicallyunsaturated monomer, epoxy resins, novolak epoxy resins, phenolic resinsand polyurethanes. The polyester may be composed of an ester formed froma polyhydric alcohol such as ethylene glycol, diethylene glycol,propylene glycol and polyethylene glycol, having a molecular weight ofbetween 300 and 4,000, together with phthalic acid, maleic acid, fumaricacid, itaconic acid, aconitic acid or anhydrides of the same.

The esters above identified are mixed or dispersed in, preferably, 20-50percentby weight of ethylenically unsaturated monomer which may consistof styrene,

vinyltoluene, methylstyrene, dimethylstyrene,methyl-alpha-methylstyrene, o-, mand pbromostyrene, dibromostyrenes, 0-,mand pchlorostyrene, dichlorostyrenes, diiallyl phthalate, vinylacetate, methyl methacrylate, or divinylbenzene. The fire retardantsalts are added to the composition in the proportion of 3-15 percent.

The uncured resins operable herein can also be epoxy resins such as thediglycidyl either of Bisphenol A (e.g. Epon 828) or aprepolymer ofdiglycidyl ether of Bisphenol A such as Epon 1001, 1004, 1009 and 1010,having molecular weights of 1000 to 12,000. Also operable are novolakprepolymer consisting of phenol formaldehyde condensation product of300m 500 molecular weight condensed with two or more molecules ofepichlorohydrin; novolak polymers, i.e., low molecular weight or stage Aprepolymers prepared from hydroxy aromatic compounds and formaldehyde;and polyurethane precursors consisting of polyisocyanates and compoundscontaining active hydrogen. e.g., polyols, polyamines, polymercaptansand polycarboxy compounds. 7

These resins can be cured by mixing with a second component which isselected from the class of free radical initiators and active hydrogencompounds. The cured resins containing 3-15 weight percent of outcomplex fire resistant additives are fire resistant thermoset resins.Curing is efiected by conventional procedures for each type of resin.The unsaturated polyestervinyl monomer compositions are cured bymaintaining at a temprature in the range of 25-l50C for 1-2.4 hoursafter mixing with a free radical initiating catalyst, e.g., 0.2 to 1.0weight percent azo-'bis(isobutyronitrile) or 0.1 to 2.0 wt. percent ofan organic peroxide such as methylethyl ketone peroxide or 2-hydroxy-2-hydroperoxypropane, or benzoyl peroxide promoted by a small amount of anamine such as from 0.1 to about 1.5% N-dimethylaniline plus 0.02 toabout 3 wt. percent vanadium or cobalt added as a soluble salt such asthe octoate, naphthenate, or acetylacetonate.

The epoxy resins are cured over a period of ll00 hours at graduallyincreasing temperatures from 20200C after admixing with a hardener inthe ratio of -100 pts. per 100 pts. by weight of the epoxy compound. Thehardeners contain two or more active H atoms and include diandpoly-amines, e.g., ethylenediamine, diethylenetriamine,triethylenetetramine, methylenedianiline, mixtures of amines such asCaytur 7 sold by DuPont (a mixture of m-phenylenediamine andcumenediamine) and dichlorobenzidine; polyols such as ethylene glycol orBisphenol A plus a small amount of catalyst, e.g., tributylamine,N-dimethylor N-diethyl-aniline; polymercaptans such as ethanedithiol,tetra-ester formed from pentaerythritol and mercaptopropionic acid;anhydrides of di or polycarboxy acids. Similar mixtures of hardeners andcatalyst with the novolak-epoxy compositions are cured in thetemperature range of 200C over a period of l-100 hours.

The polyurethanes can be prepared from polyisocyanates such as methylenebis-phenylisocyanate, tolylene diisocyanate, and polyisocyanates byreaction with active hydrogen-containing compounds. The polyisocyanatescan be blocked, e.g., with phenols, and if desired can be admixed withthe second component of the polyurethane resin producing materials, thelatter containing the complex fire retardant additives of thisinvention. The more common practice is to store the non-blockedpolyisocyanates, and the second component individually and to combinethem just prior to application and curing. The second component is apolyfunctional compound such as a polyol, polyamine, polythiol, etc.,and can be stored for long periods of time after adding our additives.These fire retardant compositions containing from 3-15 wt. percent ofour fire resistant additive together with the blocked polyisocyanatescan be stored for equally long periods of time without change until suchtime as it is desired to cure them. The curing is performed as follows:the mixtures comprising polyisocyanate, second component, and ouradditive are heated and the blocking agent, when used, e.g., phenols, isdistilled out under reduced pressure following which the system can becured by further heating in the range of 50-150C for 1-24 hours.

Finally, phenolic resins containing the fire retardant additives of thisinvention in amounts of 3-15 wt. percent are cured by admixing with 5-10wt. percent of hexamine (i.e., hexamethylenetetramine) and heating inthe range of 20200C for from 1 to about 24 hours.

The number of individual compositions which, when combined with resinsimpart substantial fire retardance, is quite large. All of thecompounds, however, fell under the general formula:

1n the above formula, the symbols represent the moieties listed. 1n thecase of R and R both cannot be (-NH,) simultaneously.

M B, Al, Sn, Ti, Si, P, PO, PS, Sb, SbO, V, V0, As,

3 X F, Cl, Br, 0, OH, N, NH-P(O) (Cl)NH,, RNH,

(-OC,C1,,) (pentachlorophenoxy) z NH,-, R'NR-, (=NH) R and R H, NH,,CONH,, Alkyl, Aryl A NH Y, Y= Br, -Cl, OH, CNO, OCN,

-SNC,-CNS a= 1 or 2 b==2, 3, 4 or5 c 0, l, 2 or 3 n 0, 1-12 inclusive p0, 1-12 inclusive Specific compounds are listed to exemplify types ofadditives of the above formula: P(NH -3NH,CI,

PCl,(OC Cl )-Nl-1 Cl, POC1,(NH,-CONH,) ZnCl,( N11,) TiCl (Nl-1 andothers demonstrated in the following examples.

EXAMPLE I A 3-liter, 3-neck flask was fitted with a mechanical stirrer,a through-tube and a reflux condenser, connected by means of a gasdispersion tube to a slightly acidic (yellow) bromothymol blueindicating solution. The flask was charged with 1,000 cc of dry benzeneand 0.5 mol of P 0 The reaction flask was immersed in an ice bath cooledto 10C, and anhydrous ammonia was bubbled through the solution until itbecame saturated shown by the color change to blue in the indicatingsolution. The fine white crystalline product which resulted readilyhydrolized. Its melting point was determined to be 160C. Assuming thatthe water of reaction stayed with the amido phosphorous compound whichformed according to the following reaction, the yield was quantitative:

o o IYIH NH,

4NH3 ZHgO. g I NH, NH;

Apparently the water was retained as an hydrate. The product wasobtained by filtering under suction.

9.25 parts of GR 941 (a general purpose polyester manufactured by theMarco Division, W. R. Grace & Co.) was weighed out into an aluminum panarld then 2.25 parts of the above adduct were added with vigorousstirring. This was immediately followed by the addition of 3 parts ofstyrene and 0.15 parts of cobalt octoate solution (12% cobalt). 0.] partof dimethylaniline and 0.02 part of 30% H O, in water. 1n about 15minutes, spontaneous warming began to occur. The mixture was poured intoan aluminum container to make flame test samples 5 inches long and )6inch thick, which were allowed to stand for one hour at roomtemperature. The samples were then placed in an oven maintained at C forone hour. The resultant wellcured resin self-extinguished in 60 secondswhen tested by ASTM test D635.

EXAMPLE ll Ammonia gas was bubbled into a solution of 77.0 grams (0.5mols) of FCC], in 2,350 grams of carbon tetrachloride. The flask wascooled in ice water to maintain the reaction temperature of the solutionbelow 20C. A white crystalline solid separated progressively. When 24grams of NH, were absorbed, the ammonia feed was cut off and the productwas filtered. On analysis it was found to contain of C0,. The productanalysis approximated that for a mixture of NH Cl and wherein n 2.5. The2.5 value was evidence of a mixture of compounds in which n 2 and 3respectively. The NH CI comprises about 50 percent of the mixture.

Two grams of the above was thoroughly mixed with 8.5 grams of an epoxyresin (Epon 828, Shell Chemical Co., epoxy equivalent l75-2l0,M.W.350-400) and 1.0 grams of diethylenetriamine. This mixture wasallowed to stand for one hour at room temperature during which time thesample hardened. Thereafter a 16- hour exposure to a temperature of 100Cfollowed by 8 hours at 125C completed the curing process. Various piecesof the sample were tested for tire resistance according to ASTM burningtest D635. All pieces selfextinguished themselves in 5-l0 seconds.

EXAMPLE III The procedure of Example II was followed except that 52grams of PCl (0.25 mols) was used instead of POCl and it was dissolvedin 392 grams of pyridine instead of carbon tetrachloride. The adductcontained 42 grams of NH On analysis the solution was found to contain15 percent of the adduct and 85% pyridine. grams of Epon 828 epoxy resinwas weighed into an aluminum pan and 5 grams of 50/50 mixture of theabove adduct and styrene was mixed together. Finally 0.5 grams ofdiethylenetriamine, a catalyst which acted as a hardener, was stirredin. After one hour at room temperature and 18 hours during which timethe temperature remained at 80C, the temperature was raised to 125C for6 hours after which the sample was fully cured. When subjected to ASTMtest D635, the sample self-extinguished in 45 seconds.

To save much repetition, a number of the following examples are herereported in summary form:

EXAMPLE IV POCl NH adduct prepared by the procedure of Example I" andcontaining 90% CCl, when added to epoxy resin Epon 828 at weight percentand cured as in Example III, self-extinguished (SE) in 5 seconds afterigniting for 30 seconds in a 1-inch Bunsen burner flame. When theconcentration of the POClfGNl-I adduct was reduced to 5% of the weightof the resin, self-extinguishment in the same flame test occurred in 36seconds. The divergence from the ASTM D-635 test was simply the use of al-inch wide sample instead of 15inch wide.

EXAMPLE V When POCI,-NH, plus an equal weight of NH,Cl was mixed withgeneral purpose polyester resin GR 941 (Marco Division of W. R. Grace &Co.) dissolved in Xylene and later cured, self-extinguishment occurredin 52 seconds in the flame used in Example IV. The curing wasaccomplished by admixing the polyester resin with 0.5 wt. percentLupersol DSW (a solution of 60% methylethylketone peroxide) 0.5 wt.percent dimethylaniline and 0.2 wt. percent of cobalt octoate solution12% cobalt), allowing for an initial exotherm dissipation by standing 1hour at 25C, then heating at 100C for 4 hours or until the odor ofstyrene completely disappeared.

EXAMPLE VI When the adduct of Example V plus an equal weight of ammoniumchloride mixed in water was reacted with epoxy resin Epon 828 at 10 wt.percent and cured with 10% diethylenetriamine as in Example II, selfextinguishment occurred in 2 seconds in the flame test defined inExample IV.

EXAMPLE VII The adduct of phosphorus oxychloride and urea formed incarbon tetrachloride solution contained 5% CCl and added to epoxy resinEpon 828 in 10 wt. percent concentration and cured as in Example II, didnot ignite in the modified ASTM D635 test used in Example IV.

EXAMPLE VIII When 15 wt. percent of P 0 NH product was mixed withpolyester GR 941 (above identified) and cured as in Example I,self-extinguishment occurred in seconds after the 30 seconds ignitiontest of Example IV.

EXAMPLE IX EXAMPLE X The adduct of phosphorus pentachloride and ammonia(10:1 mole ratio) was reacted in styrene and added at 17 wt. percentconcentration to GR 941 polyester resin, which then was cured as inExample V, the cured resin self-extinguished in 5 seconds in the flametest described in Example IV.

EXAMPLE XI The adduct of phosphorus oxychloride 4.5 parts and urea 5.5parts'mixed with 5% CCI, was mixed with 8 parts of epoxy resin Epon 828and cured by the schedule given after Example XVIII. Itself-extinguished in 14 seconds in the flame test of Example IV. Whenthe respective weights were changed to 3.3 for phosphorus oxychloride,4'for urea and 7.3 for the epoxy resin, the state of cure was excellentand self-extinguishment occurred in one second.

EXAMPLE XII The adduct of zinc chloride and ammonia reacted in acetoneand added to polyester GR 941 at 10 wt. percent, and cured as in ExampleV, self-extinguished in 20 seconds in the flame test of Example IV.

EXAMPLE XIII When 15 wt. percent of the adduct of Example XII was addedto epoxy resin Epon 828 and cured by the schedule cited below, the curedresin self-extinguished in 30 seconds in the flame test described inExample IV.

EXAMPLE XIV When vanadium oxychloride was reacted with ammonia in carbontetrachloride solution and wt. percent of the partially dried productcontaining about 15% CCl was added to polyester GR 941 and the mixturewas then cured as in Example V, the cured resin self-extinguished in 36seconds in the flame test of Example IV.

EXAMPLE XV When 15 wt. percent of the vanadium oxychlorideammonia adductof Example XIV was added to epoxy resin Epon 828 and cured as describedhereinafter, self-extinguishment occurred in 31 seconds in the flametest of Example IV.

EXAMPLE XVI Antimony trichloride in carbon tetrachloride solution wasreacted with ammonia and 15 wt. percent of the adduct (including 85% CClwas added to epoxy resin Epon 828 and cured as described after ExampleXVIII, the flame test of Example IV gave selfextinguishment in 3seconds.

EXAMPLE XVII When 15 wt. percent of the antimony adduct of Example XVIwas added to polyester GR 941 and cured as in Example V, ASTM D 635resulted in selfextinguishment in 50 seconds.

EXAMPLE XVIII The adduct of titanium chloride and ammonia reacted incarbon tetrachloride and containing CCl solvent was added in 15 wt.percent concentration to epoxy resin Epon 828 and cured. The cured resinselfextinguished in 39 seconds.

In Examples VIII to XVIII inclusive, the(M,,X,,),,,(RNH,),, preparationand the polyester resin cures were conducted in the following manner:

The adduct was prepared by a process analogous to the adduct preparationin Example II, i.e., the ingredients were placed in an excess of thesolvent noted (carbon tetrachloride, acetone, styrene). The flask wascooled in ice water to keep the reaction temperature below 20C, and atthe end of the reaction, the crystallne solid adduct was filtered fromthe solution. In Example VIII, 2.5 parts of the filtered adduct wereground with 4.3 parts of styrene and then the slurry was stirred into7.85 parts of polyester resin GR 941. In Examples IX, X, XII, XIV andXVII, the styrene was omitted. Thereafter, 0.2 parts of cobalt octoatesolution containing 12% cobalt, 0.1 part of N-dimethylaniline and 0.05parts of hydrogen peroxide were mixed into the polyester. The resinbegan to cure immediately at room temperature and heated spontaneouslyto over C in 10 minutes. The resin was poured into sample molds andplaced in an oven at C for 18 hours, followed by a bake at 100C for 2hours.

The epoxy resins in the above examples, XI, XIII, XV, XVI and XVIII,were cured as follows: parts of epoxy resin Epon 828 mixed with 4.5parts of diethylenetriamine. The resin was poured into sample molds,allowed to stand 1 hour and placed in an oven for 4 hours, then placedin a C oven for 4 hours and finally in an oven at C for 16 hours.

As has been stated, it is not necessary for the resin to be in uncuredform or dissolved in order for the reaction with the adducts to occur.The following example shows how an effective surface treatment addingmaterially to the fire resistance of a resinous mass can be preparedafter that mass has been given its form as, e.g., by molding.

EXAMPLE XIX Ten parts by weight of the additive of Example XI wereadmixed with 90 parts of phenolic-epoxy resin D.E.N. 431. The mixturewas charged to an ashtray mold and cured with 10 partsdiethylenetriamine using the heating schedule described above forExamples XI, XIII, XV, XVI and XVIII. The cured ashtray was nonburningand self-extinguished immediately in the flame test described in ExampleIV.

EXAMPLE XX Example XIX was repeated but substituting 90 g. of BMG 5120(phenolic molding compound sold by Union Carbide Corp.) in the place ofD.E.N. 431. After heating at C. and 2,000 psig pressure for 5 minutes,the cured ashtray was removed from the mold and tested as in ExampleXIX, the tray was immediately self-extinguished.

EXAMPLE XX] 60 parts of polyester resin GR 941 was thoroughly mixed with0.4 parts of Lupersol DSW (methyl ethyl Ketone peroxide) and then 0.2parts of cobaltoctoate was added. The mixture was poured into resinmolds which were placed in an oven maintained at 80C for 64 hours. Allsamples showed excellent cures. The samples were removed and placed in avessel where they were treated for 2 hours with the vapor of phosphorustrichloride which saturated the atmosphere in the vessel, and at the endof this time the samples were treated for a further period of 2 hourswith ammonia vapor. When these samples were subjected to the tests forflame resistance ASTM D-635, the treated resin .samplesself-extinguished in 45 seconds.

Accordingly, any formed shape can be given a treatment which penetratesat least the surface layers of the resin and confers very effectiveflame-proofing to the resinous mass.

EXAMPLE XXII Polystyrene foam was prepared by steamheating expandiblestyrene beads (from Koppers Co.) which, prior to expansion, were treatedwith PC], and NH, vapor as in Example XV. The resultant foam melted butwould not burn in the ASTM test for foams.

EXAMPLE xxm (Fire retardant resins formed by the in situ method) Rigidpolyurethane samples were prepared by curing a polyisocyanate sold bythe Upjohn Company and reported to be a mixture of: I

NCO I-|ICO I: and I NCO NCO NC 0 onic acid. Equal weights of thepolyisocyanate and the tetramercaptan were thoroughly blended, warmedand evacuated in a vacuum chamber until all dissolved volatiles wereremoved. This was indicated by the cessation of bubbling and requiredabout h hour. The resin was poured into sample molds which were placedin an 80C oven for 64 hours to develop hard cures. When cured, thesamples were subjected to PCl vapor for about 2 hours; and followingthis, ammonia vapor was admitted to the chamber and maintained for about3 hours. The adduct formed on the surface and penetrated the surfacelayers of the resin. When these samples were tested, theyself-extinguished in 3 seconds or less.

EXAMPLE XXIV EXAMPLE XXV 60 gr. of GR 941 polyester general purposeresin, Marco Division, W. R. Grace & Co., was thoroughly mixed with 0.4gr. of Lupersol DSW methylethyl ketone peroxide (60 percent solution).Then 0.2sgr. of cobalt octoate was added. After a few minutes the resinwas poured into sample molds which were placed in an 80C oven for anhour, then at 100C for 7 hours. Very good cures resulted. The resinsamples were then treated successively with phosphorus trichloride vaporand ammonia vapor as described in Example XXI. These samples were testedaccording to ASTM D-635 procedure. The samples self-extinguished in 2seconds or less.

Where self-extinguishment is used in the examples and specificationsherein, it is defined as selfextinguished after ignition for 30 secondsin a Bunsen burner flame from 1 to 1.5 inches high, either according toD-635 (sample size /4 X A X 5 inches), of by modified D-635 wherein theonly difference is in sample size (V4 X l X 5 inches).

EXAMPLE XXVI An epoxy resin mixture consisting of 92 parts Epon 828 and8 parts of allylglycidyl ether was cured by admixing with l() partstriethylenetetramine and, after an hour at room temperature, was placedin an oven at 50C, and the temperature of the oven was graduallyincreased to C over a 4 hour period. It was then left at 125C for 16hours to give a cured resin having a hardness of Shore D 92. The curedresin was exposed to PCI vapors for an hour followd by ammonia vaporsfor an hour. This resin would not ignite in less than 30 seconds, andwhen finally ignited, it self-extinguished in less than 5 seconds. Thisexample demonstrates the incorporation of an alpha-olefinic monomer(i.e., allylglycidyl ether) in the resin matrix, subsequent addition ofPCl, to the olefin group, followed by addition of ammonia to the PCl,moiety, and thus fireproofing the surface of the resin. The overallchemical reactions may be represented as follows:

Resin matrix-cHT-cH 0H -o-oH, cH-0H,

Resin matra-Cm-CHQH Oom ofi onm rvatcl l NHg What is claimed is:

1. The process of preparing flame resistant resins which consists ofsubjecting cured resins of the class consisting of cured polyurethaneresins, cured polyester resins, cured polystyrene resins, cured epoxyresins to the vapor of phosphorus trichloride and subsequentlyimmediately subjecting the PCl, treated resin to the vapors of ammoniafor a period of about 2 hours whereby the resin has a halide moietyconcentration of 5-20 percent by weight of the resin.

2. The process of producing a flame resistant layer at and adjacent tothe surface of a formed resinous body which consists in treating aformed resinous body selected from the class of cured formed polyesterbodies, cured formed epoxy resinous bodies, cured formed polyurethanebodies and cured formed polystyrene bodies to the vapors of phosphorustrichloride for a period of about 2 hours, withdrawing the phosphorustrichloride vapor and then subjecting the treated resinous body to thevapors of ammonia for a period of about 2 hours whereby a flameresistant layer comprising the resin and -520 percent of the resin ofthe adduct of phosphorus trichloride and ammonia is formed on thesurface of the body.

3. The cured resin product of claim 1.

4. The cured resin product of claim 2.

2. The process of producing a flame resistant layer at and adjacent tothe surface of a formed resinous body which consists in treating aformed resinous body selected from the class of cured formed polyesterbodies, cured formed epoxy resinous bodies, cured formed polyurethanebodies and cured formed polystyrene bodies to the vapors of phosphorustrichloride for a period of about 2 hours, withdrawing the phosPhorustrichloride vapor and then subjecting the treated resinous body to thevapors of ammonia for a period of about 2 hours whereby a flameresistant layer comprising the resin and -5-20 percent of the resin ofthe adduct of phosphorus trichloride and ammonia is formed on thesurface of the body.
 3. The cured resin product of claim
 1. 4. The curedresin product of claim 2.